1. Field of the Invention
The present invention relates to an image display apparatus of a projection type, applying an oblique projection optical system therein, for projecting a picture of an image generation source onto a screen of rear-projection type, from a direction inclined thereto, and also a Fresnel lens sheet and a screen of rear-projection type, to be used in such the image display apparatus.
2. Description of the Related Art
For coping with thinning of the image display apparatus, in particular, of the projection type, there is already known the structure of applying the inclined or oblique structure, for projecting an enlarged picture onto a screen from a direction inclined or oblique thereto, by using a reflection mirror, i.e., so-called an oblique projection optical system. In this instance, since the enlarged picture is projected onto the screen, obliquely (i.e., in a manner of defining a predetermined angle between a perpendicular line drawn from the principle plane on the screen and an incident direction of a light at a center of the enlarged picture), the image projected on the screen is distorted. Then, for correcting such the distortion, there is also already known the structure of an image display apparatus, adopting within a portion of the reflection mirror a curved surface reflection mirror, which is formed with a curved surface, for example, in Japanese Patent Laying-Open No. 2002-341452 (2002).